The present disclosure relates to a driving device used in a copier, a printer, a facsimile, a multifunction peripheral of them, or the like, and a sheet feeding device and an image forming apparatus including the driving device.
Conventionally, a color image forming apparatus is configured to be capable of switching between monocolor (monochrome) image formation using black color and multicolor (color) image formation. The monocolor image formation and the multicolor image formation have different image formation processing speeds, and a mechanism for switching between the monocolor image formation and the multicolor image formation is provided. With this switching mechanism, a structure of the image forming apparatus is unnecessarily complicated, and cost of the image forming apparatus is increased.
Therefore, an image forming apparatus is known, which includes a driving device for driving an image forming unit that stores black color developer to be used both for the monocolor image formation and for the multicolor image formation. When forming a monochrome image, a motor is driven to rotate in a first direction, a drive gear rotates in the first direction, and a swing gear moves to a first position so as to be engaged with a first gear train. A black gear positioned at an end of the first gear train drives a black color image forming unit to rotate at a first rotation speed. On the other hand, when forming a color image, the motor is driven to rotate in a second direction, the drive gear rotates in the second direction, the swing gear moves to a second position so as to be engaged with a second gear train having a different reduction ratio from the first gear train. A black gear positioned at an end of the second gear train drives the black color image forming unit to rotate at a second rotation speed. In this way, only by changing the rotation direction of the single motor, monochrome image formation operation and color image formation operation can be switched.
In addition, a driving device is known, which includes a drive gear disposed to be capable of rotating in a first direction and in a second direction according to a rotation direction of a motor, and a swing gear configured to be engaged with the drive gear and to be capable of swing between a first position and a second position according to a rotation direction of the motor by a rotation drive force transmitted to the drive gear. In this driving device, a bracket having a slide hole for holding the swing gear in a rotatable and swingable manner is configured to have a larger stiffness than the swing gear and a smaller friction coefficient than the frame. In this way, when a rotation shaft of the swing gear rotates and swings repeatedly in the slide hole, sliding performance of the rotation shaft of the swing gear is not decreased, and fluctuation in a rotation torque or a rotation speed in a drive output part can be suppressed.